There is a table (which is a kind of instrument):
- It is round: therefore it is a place of equal communication = equality
of all sitting positions (like the round table for political
negotiations, a table in a caffe-bar, etc...).
- Three people sitting around: three is the minimum of the public space
= public communication (two is not enough, since two is private).
- Round & three people can form a kind of spiritual(-istic) circle,
which means that they are absorbed, connected into a debate - into
something common (in our case - sound output).